Polypropylene fibres

ABSTRACT

A polypropylene fiber including greater than 50% by weight of a first isotactic polypropylene produced by a Ziegler-Natta catalyst, from 5 to less than 50% by weight of a second isotactic polypropylene produced by a metallocene catalyst and up to 15% by weight of a syndiotactic polypropylene (sPP).

The present invention relates to polypropylene fibres and to fabricsproduced from polypropylene fibres.

Polypropylene is well known for the manufacture of fibres, particularlyfor manufacturing non-woven fabrics.

EP-A-0789096 and its corresponding WO-A-97/29225 discloses suchpolypropylene fibres which are made of a blend of syndiotacticpolypropylene (sPP) and isotactic polypropylene (iPP). Thatspecification discloses that by blending from 0.3 to 3% by weight ofsPP, based on the total polypropylene, to form a blend of iPP-sPP, thefibres have increased natural bulk and smoothness, and non-woven fabricsproduced from the fibres have an improved softness. Moreover, thatspecification discloses that such a blend lowers the thermal bondingtemperature of the fibres. Thermal bonding is employed to produce thenon-woven fabrics from the polypropylene fibres. The specificationdiscloses that the isotactic polypropylene comprises a homopolymerformed by the polymerisation of propylene by Ziegler-Natta catalysis.The isotactic polypropylene typically has a weight average molecularweight Mw of from 100,000 to 4,000,000 and a number average molecularweight Mn of from 40,000 to 100,000, with a melting point of from about159 to 169° C. However, the polypropylene fibres produced in accordancewith this specification suffer from the technical problem that theisotactic polypropylene, being made using a Ziegler-Natta catalyst, doesnot have particularly high mechanical properties, particularly tenacity.

WO-A-96/23095 discloses a method for providing a non-woven fabric with awide bonding window in which the non-woven fabric is formed from fibresof a thermoplastic polymer blend including from 0.5 to 25 wt % ofsyndiotactic polypropylene. The syndiotactic polypropylene may beblended with a variety of different polymers, including isotacticpolypropylene. The specification includes a number of examples in whichvarious mixtures of syndiotactic polypropylene with isotacticpolypropylene were produced. The isotactic polypropylene comprisedcommercially available isotactic polypropylene, which is produced usinga Ziegler-Natta catalyst. It is disclosed in the specification that theuse of syndiotactic polypropylene widens the window of temperature overwhich thermal bonding can occur, and lowers the acceptable bondingtemperature.

WO-A-96/23095 also discloses the production of fibres from blendsincluding syndiotactic polypropylene which are either bi-componentfibres or bi-constituent fibres. Bi-component fibres are fibres whichhave been produced from at least two polymers extruded from separateextruders and spun together to form one fibre. Bi-constituent fibres areproduced from at least two polymers extruded from the same extruder as ablend. Both bi-component and bi-constituent fibres are disclosed asbeing used to improve the thermal bonding of Ziegler-Natta polypropylenein non-woven fabrics. In particular, a polymer with a lower meltingpoint compared to the Ziegler-Natta isotactic polypropylene, for examplepolyethylene, random copolymers or terpolymers, is used as the outerpart of the bi-component fibre or blended in the Ziegler-Nattapolypropylene to form the bi-constituent fibre.

EP-A-0634505 discloses improved propylene polymer yarn and articles madetherefrom in which for providing yarn capable of increased shrinkagesyndiotactic polypropylene is blended with isotactic polypropylene withthere being from 5 to 50 parts per weight of syndiotactic polypropylene.It is disclosed that the yarn has increased resiliency and shrinkage,particularly useful in pile fabric and carpeting. It is disclosed thatthe polypropylene blends display a lowering of the heat softeningtemperature and a broadening of the thermal response curve as measuredby differential scanning calorimetry as a consequence of the presence ofsyndiotactic polypropylene.

U.S. Pat. No. 5,269,807 discloses a suture fabricated from syndiotacticpolypropylene exhibiting a greater flexibility than a comparable suturemanufactured from isotactic polypropylene. The syndiotacticpolypropylene may be blended with, inter alia, isotactic polypropylene.

EP-A-0451743 discloses a method for moulding syndiotactic polypropylenein which the syndiotactic polypropylene may be blended with a smallamount of a polypropylene having a substantially isotactic structure. Itis disclosed that fibres may be formed from the polypropylene. It isalso disclosed that the isotactic polypropylene is manufactured by theuse of a catalyst comprising titanium trichloride and an organoaluminiumcompound, or titanium trichloride or titanium tetrachloride supported onmagnesium halide and an organoaluminium compound, i.e. a Ziegler-Nattacatalyst.

EP-A-0414047 discloses polypropylene fibres formed of blends ofsyndiotactic and isotactic polypropylene. The blend includes at least 50parts by weight of the syndiotactic polypropylene and at most 50 partsby weight of the isotactic polypropylene. It is disclosed that theextrudability of the fibres is improved and the fibre stretchingconditions are broadened.

It is further known to produce syndiotactic polypropylene usingmetallocene catalysts as has been disclosed for example in U.S. Pat. No.4,892,851.

Recently, metallocene catalysts have also been employed to produceisotactic polypropylene. Isotactic polypropylene which has been producedusing a metallocene catalyst is identified hereinafter as miPP. Fibresmade of miPP exhibit much higher mechanical properties, mainly tenacity,than typical Ziegler-Natta polypropylene based fibres, hereinafterreferred to as ZNPP fibres. However, this gain in tenacity is onlypartly transferred to non-woven fabrics which have been produced fromthe miPP fibres by thermal bonding. Indeed, fibres produced using miPPhave a very narrow thermal bonding window, the window defining a rangeof thermal bonding temperatures through which, after thermal bonding ofthe fibres, the non-woven fabric exhibits the best mechanicalproperties. As a result, only a small number of the miPP fibrescontribute to the mechanical properties of the non-woven fabric. Also,the quality of the thermal bond between adjacent miPP fibres is poor.Thus known miPP fibres have been found to be more difficult to thermallybond than ZNPP fibres, despite a lower melting point.

WO-A-97/10300 discloses polypropylene blend compositions wherein theblend may comprise from 25% to 75% by weight metallocene isotacticpolypropylene and from 75 to 25% by weight Ziegler-Natta isotacticpolypropylene copolymer. The specification is fundamentally directed tothe production of films from such polypropylene blends.

U.S. Pat. No. 5,483,002 discloses propylene polymers havinglow-temperature impact strength containing a blend of onesemi-crystalline propylene homopolymer with either a secondsemi-crystalline propylene homopolymer or a non-crystallising propylenehomopolymer.

EP-A-0538749 discloses a propylene copolymer composition for productionof films. The composition comprises a blend of two components, the firstcomponent comprising either a propylene homopolymer or a copolymer ofpropylene with ethylene or another alpha-olefin having a carbon numberof 4 to 20 and the second component comprising a copolymer of propylenewith ethylene and/or an alpha-olefin having a carbon number of 4 to 20.

It is known in the art to blend into a polypropylene produced using aZiegler-Natta catalyst a second component comprising a randompolypropylene, typically in an amount of around 20 to 50 wt % of theblend. Such a blend has been found to provide good thermal bonding whenfibres produced from the blend are thermally bonded to form a non-wovenfabric. The good thermal bonding results from a temperature overlap ofthe melting points of the Ziegler-Natta polypropylene and the randompolypropylene. The thermal bonding is also achieved as a result of boththe Ziegler-Natta polypropylene and the random polypropylene havingrelatively broad molecular weight distributions which provides a goodblend and thus tends to enhance the thermal bondability of fibres.

It is an aim of the present invention to broaden the thermal bondingwindow of ZNPP fibres. It is a further aim of the invention to providenon-woven fabrics of ZNPP fibres exhibiting improved mechanicalproperties, in particular tenacity.

It is known that polypropylene fibres, and non-woven fabrics made ofpolypropylene fibres, tend to feel rough to the touch. It is also an aimof the present invention to improve the softness of polypropylenefibres.

The present invention provides a polypropylene fibre including greaterthan 50% by weight of a first isotactic polypropylene produced by aZiegler-Natta catalyst, from 5 to less than 50% by weight of a secondisotactic polypropylene produced by a metallocene catalyst and up to 15%by weight of a syndiotactic polypropylene (sPP).

The polymeric fibre may preferably include from 60 to 80% by weight ofthe first isotactic polypropylene and from 10 to less than 50%, morepreferably from 20 to 40% by weight of the second isotacticpolypropylene.

Preferably, up to lot by weight of the syndiotactic polypropylene (sPP)is included in the polypropylene fibre. The addition of sPP improves thesoftness of the fibres.

The first polypropylene produced by the Ziegler-Natta catalyst (ZNPP)may be a homopolymer, copolymer or terpolymer.

The second polypropylene produced by the metallocene catalyst (miPP) isa homopolymer, copolymer, being either a random or block copolymer, orterpolymer of isotactic polypropylene produced by a metallocenecatalyst.

Preferably, the second polypropylene has a dispersion index (D) of from1.8 to 8. Preferably, the second polypropylene has a melting temperaturein the range of from 130 to 161° C. for homopolymer and a meltingtemperature of from 80 to 160° C. for a copolymer or terpolymer.

The miPP preferably has a melt flow index (MFI) of from 1 to 2500 g/10mins. In this specification the MFI values are those determined usingthe procedure of ISO 1133 using a load of 2.16 kg at a temperature of230° C.

More preferably, the second polypropylene homopolymer or copolymer hasan Mn of from 30,000 to 130,000 kDa and the MFI may range from 1 to 2000g/10 min and preferably from 5 to 90 g/10 min for spunlaid or for staplefibres.

Preferably, the first polypropylene has a dispersion index (D) of from 3to 12. Preferably, the first polypropylene has a melting temperature inthe range of from 80 to 169° C., more preferably a melting temperatureof from 159 to 169° C. for homopolymer and a melting temperature of from80to 168° C. for a copolymer or terpolymer. A typical meltingtemperature for ZNPP is 162° C.

The ZNPP preferably has a melt flow index (MFI) of from 1 to 100 g/10mins.

More preferably, the first polypropylene homopolymer has a MFI rangingfrom 15 to 60 g/10 min for spunlaid or 10 to 30 g/10 min for staplefibres

The sPP is preferably a homopolymer or a random copolymer with a RRRR ofat least 70%. The sPP may alternatively be a block copolymer having ahigher comonomer content, or a terpolymer. If the comonomer content isabove 1.5 wt %, the sPP tends to become sticky, thus resulting inproblems when spinning the fibres or thermally bonding the fibres.Preferably, the sPP has a melting temperature of up to about 130° C. ThesPP typically has two melting peaks, one being around 112° C. and theother being around 128° C. The sPP typically has an MFI of from 0.1 to1000 g/10 min, more typically from 1 to 60 g/10 min. The sPP may have amonomodal or multimodal molecular weight distribution, and mostpreferably is a bimodal polymer in order to improve the processabilityof the sPP.

The present invention further provides a fabric produced from thepolypropylene fibre of the invention.

The present invention yet further provides a product including thatfabric, the product being selected from among others a filter, personalwipe, diaper, feminine hygiene product, incontinence product, wounddressing, bandage, surgical gown, surgical drape and protective cover.

The present invention is predicated on the discovery by the presentinventor that when blended with a major amount of ZNPP, miPP causesimproved thermal bonding of the ZNPP, without a significant modificationof the mechanical properties of the fibres themselves. The presentinventor has discovered surprisingly that by blending less than 50% byweight miPP into the Ziegler-Natta polypropylene, this provides enhancedthermal bonding of the Ziegler-Natta polypropylene despite the miPPhaving a narrower molecular weight distribution than that of the ZNPP,and also the random PP employed in the prior art referred tohereinabove, which would have been considered by the person skilled inthe art to have reduced the thermal bonding effect.

Indeed, narrowing molecular weight distribution is known to reduce thebonding window temperature of the fibre. Thus the present inventor hasdiscovered surprisingly that by blending of miPP into ZNPP, with themiPP having a typical melting range of from about 130° C. to about 161°C., which is lower than the typical melting range of ZNPP of from about159° C. to about 169° C., the improvement in thermal bonding is achievedas a result of this lower melting point of the miPP, despite thenarrower molecular weight distribution of the miPP which would suggestpoorer thermal bonding. As a consequence, at any given thermal bondingtemperature, more fibres are thermally bonded compared to pure Zn PPfibres and the bonding strength improves, thereby improving themechanical properties of the non-woven fabric produced thereby.

The present invention will now be described by way of example only withreference to the accompanying drawings, in which:

FIG. 1 is a graph showing the molecular weight distributions for atypical ZNPP and a typical random PP and for a typical miPP and

FIGS. 2 and 3 are graphs showing the relationship between, respectively,elongation (%) at maximum drawing force and fibre tenacity (cN/tex) atmaximum drawing force with respect to miPP amount for fibres producedfrom blends of miPP and znPP.

Referring to FIG. 1, there is shown the common molecular weightdistribution for a typical ZNPP and a typical random PP (line B), andalso the molecular distribution for a typical miPP (line A). It may beseen that for both the ZNPP and the random PP, these both exhibit abroad molecular weight distribution compared to miPP which show that theZNPP and the random PP may readily be blended together. In contrast, themiPP has a much narrower molecular weight distribution which would havebeen considered, when blended into a ZNPP, to have reduced the thermalbonding. In contrast, the present inventor has found that despite thenarrow molecular weight distribution of the miPP, nevertheless when themiPP is blended in an amount of from 10 to 50% by weight into the ZNPP,the thermal bonding of the ZNPP is improved without significantmodification of the mechanical properties of the blend.

An industrial thermal bonding process for producing a non-woven fabricemploys the passage at high speed of a layer of fibres to be thermallybonded through a pair of heated rollers. This process thus requiresrapid and uniform melting of the surfaces of adjacent fibres in orderfor a strong and reliable thermal bond to be achieved. The addition ofmiPP to the ZNPP tends to lower the thermal bonding temperature of thefibres so as to broaden the thermal bonding temperature range or“window” for the fibres, thereby to increase the ease of thermal bondingthe fibres together. Thus the incorporation of miPP into ZNPP enablesthe maximum strength of the non-woven fabric to be greatly increased asa result of this increased thermal bond formation between adjacentfibres.

The miPP employed in accordance with the invention has a narrowmolecular weight distribution, typically having a dispersion index D offrom 1.8 to 4, more preferably from 1.8 to 3. The dispersion index D isthe ratio Mw/Mn, where Mw is the weight number average molecular weightand Mn is the number average molecular weight of the polymer. The miPPhas a melting temperature in the range of from 140° C. to 155° C. Theproperties of two typical miPP resins for use in the invention arespecified in Table 1.

The addition of up to 15% wt (optionally up to 10 wt %) sPP to the miPPalso has been found by the inventor to improve the softness of thefibres. As a result of the phenomenon of the rejection of small amountsof sPP to the surface of the fibres, the inventor has found that thesoftness of the fibres may be increased using only small amounts of sPP,for example from 0.3 wt % sPP in the sPP/miPP/ZNPP blend. Since theblending of sPP into miPP and ZNPP permits a lower thermal bondingtemperature to be employed than would be employed for pure miPP fibres,and since lower thermal bonding temperatures tend to reduce theroughness to the touch of a non-woven fabric produced from the fibres,introducing sPP in accordance with the invention into miPP and ZNPPimproves the softness of the non-woven fabric. The composition of atypical sPP for use in the invention is specified in Table 1.

Furthermore, when sPP is incorporated into miPP and ZNPP to form blendsthereof, and when those blends are used to produce spun fibres, the sPPpromotes fibres having improved natural bulk, resulting in improvedsoftness of the non-woven fabric.

In addition, the use of miPP in blends with ZNPP and optionally sPP inaccordance with the invention tends to provide fibres which can be morereadily spun as compared to known ZNPP fibres. The substantial reductionof such long chains in the molecular weight distribution of the miPPtends to reduce built-in stress during spinning thereby to allow in anincrease in the maximum spin speed for the fibres of the miPP/ZNPPblends in accordance with the invention.

The incorporation of sPP into miPP and ZNPP to form blends thereofprovides a broader thermal bonding window. The thermal bondingtemperature of fibres produced from such blends is also Slightly lower.The fibres and non-woven fabrics produced from the blends have increasedsoftness and the spun fibres have natural bulk as a result of theintroduction of sPP into the miPP and ZNPP. The fibres also haveimproved resiliency compared to known polypropylene ZNPP fibres as aresult of the use of sPP. Furthermore, the use of miPP allows theproduction of finer fibres, resulting in softer fibres and a morehomogeneous distribution of the fibres in the non-woven fabric.

Although it was known prior to the present invention to use a secondpolymer in fibres, it has not heretofore been proposed to employ miPP ina blend with ZNPP for the production of fibres. Efficient thermalbonding of the fibres is required to transfer the outstanding mechanicalproperties of the fibres into non-woven fabrics. The spinnability of thefibres produced using miPP/ZNPP blends in accordance with the inventionis not significantly modified as compared to known fibres.

The fibres produced in accordance with the invention may be eitherbi-component fibres or bi-constituent fibres. For bi-component fibres,miPP and ZNPP are fed into two different extruders. Thereafter the twoextrudates are spun together to form single fibres. For thebi-constituent fibres, blends of miPP/ZNPP are obtained by: dry blendingpellets, flakes or fluff of the two polymers before feeding them into acommon extruder; or using pellets or flakes of a blend of miPP and ZNPPwhich have been extruded together and then re-extruding the blend from asecond extruder.

When the blends of ZNPP/miPP are used to produce fibres in accordancewith the invention, it is possible to adapt the temperature profile ofthe spinning process to optimise the processing temperature yetretaining the same throughput as with pure miPP. For the production ofspunlaid fibres, a typical extrusion temperature would be in the rangeof from 200° C. to 260° C., most typically from 230° C. to 250° C. Forthe production of staple fibres, a typical extrusion temperature wouldbe in the range of from 230° C. to 330° C., most typically from 270° C.to 310° C.

The fibres produced in accordance with the invention may be producedfrom ZNPP/miPP blends having other additives to improve the mechanicalprocessing or spinnability of the fibres. The fibres produced inaccordance with the invention may be used to produce non-woven fabricsfor use in filtration; in personal care products such as wipers,diapers, feminine hygiene products and incontinence products; in medicalproducts such as wound dressings, surgical gowns, bandages and surgicaldrapes; in protective covers; in outdoor fabrics and in geotextiles.Non-woven fabrics made with the ZNPP/miPP fibres of the invention can bepart of such products, or constitute entirely the products. As well asmaking non-woven fabrics, the fibres may also be employed to make aknitted fabric or a mat. The non-woven fabrics produced from the fibresin accordance with the invention can be produced by several processes,such as air through blowing, melt blowing, spun bonding or bonded cardedprocesses. The fibres of the invention may also be formed as a non-wovenspunlace product which is formed without thermal bonding by fibres beingentangled together to form a fabric by the application of a highpressure-fluid such as air or water.

The present invention will now be described in greater detail byreference to the following non-limiting examples.

EXAMPLES 1

In accordance with this example, the properties of a non-woven productcomposed of polypropylene fibres incorporating up to 50 wt % miPP withthe remainder being znPP were compared to fibres composed of pure miPP.Thus the pure miPP had an MFI of 32 g/10 mins and a Mw/Mn ratio of 3.The znPP had an MFI of 12 g/10 mins and an Mw/Mn ratio of 7. A blend,hereinafter called Poly 1, of the miPP and the znPP with a weight ratioof 33 wt % miPP/67 wt % znPP was produced. Fibres were made both of theblend Poly 1 and of the pure miPP. The fibres were spun by a long spinprocess, with the polymer temperature in the spinnerets being 280° C.The fibre titre after spinning was 2.3 dtex and the fibre titre afterdrawing was 2.1 dtex. The fibres were texturised and cut after thedrawing step. They were then stored in bales of 400 kg for 10 days. Thefibres were then subjected to carding and bonding at a speed of 110m/minute. Thereafter, non-woven products having a weight of 20 g/m² wereproduced by thermal bonding. The thermal bonding temperature and themechanical properties of the non-wovens thereby produced both for thePoly 1 and the pure miPP are shown in Table 2.

It may be seen from Table 2 that the mechanical properties of thenon-woven thermally bonded product of Poly 1 are greater than that forpure miPP at corresponding thermal bonding temperatures.

EXAMPLE 2

In accordance with this example, various blends of znPP and miPP weremade and the compositions of the blends are specified in Table 3.

The miPP had an MFI of 13 g/10 min. The znPP was the same as thatemployed in Example 1. The blends were prepared by dry blending pelletsof the components and pouring the dry blend into the feeder of theextruder immediately after blending. Fibres were then produced from theextruded blend. The fibre was produced using a spinneret having 224holes with a length/diameter ratio of 8/0.8. The extrusion temperaturewas 285° C. with quenching air at 15° C. at a pressure of 50 Pa. Thetemperature of the drawing godets was 80° C. For each blend, fibres wereproduced under the conditions of take-up at 1600 m/min followed bydrawing with a draw ratio (SR) of 1.3. The throughput per hole wasadjusted to keep the fibre titre at around 2.5 dtex.

Table 3 shows the titre, the fibre tenacity at 10% elongation, theelongation at maximum drawing force, the fibre tenacity at maximumdrawing force (sigma@max). FIGS. 2 and 3 are graphs showing therelationship between the elongation at maximum drawing force and thefibre tenacity at maximum drawing force, respectively, with respect tothe amount of miPP in the blend.

Table 4 shows the titre, the fibre tenacity at 10% elongation, theelongation at maximum drawing force, the fibre tenacity at maximumdrawing force (sigma@max) for fibres produced as described here abovebut without drawing.

It may be noted that for a blend having up to 50 wt % miPP in the blendof znPP/miPP, the elongation at maximum drawing force and the fibretenacity at maximum drawing force are substantially constant withrespect to the miPP amount. Thus by adding miPP to a znPP/miPP blend upto amount of 50 wt % miPP, the mechanical characteristics of the fibreare not substantially modified, in particular the fibre elongation andtenacity, but, as shown in Example 1, the characteristics of the bondingof the fibres to form thermally bonded non-wovens are improved.

EXAMPLE 3

This example demonstrates the increase in bulk or softness ofpolypropylene fibres by incorporating into the blend of znPP/miPP anamount of sPP.

When polypropylene fibres are laid on a flat surface, such as a glassplate, the morphology of the fibre, in particular its degree ofstraightness or, conversely, its degree of waviness, is an indication ofthe bulk of the fibre. The fibre, which can be examined by opticalmicroscopy, can be seen to have a wavy or substantially sinusoidalmorphology, with increased waviness (i.e. a reduced pitch between peaksof adjacent waves) corresponding to increased bulk or softness of thefibre.

When sPP was added to a polypropylene homopolymer in an amount up to 15wt %, it has been found that the distance between two peaks of the wavysurface decreases, in turn meaning that the bulk or softness of thefibres increases. For example when 5 wt % sPP was blended into aZiegler-Natta polypropylene homopolymer, the distance between the peakswas 5.1 mm whereas when 15 wt % sPP was blended into the samepolypropylene, the distance between the peaks was around 4 mm. Thisdemonstrates that the bulk or softness of the fibres was increased withincreasing amount of sPP in the base polypropylene.

TABLE 1 ZNPP sPP miPP1 miPP2 MI₂ 14 3.6 32 13 Tm ° C. 162 110 and 127148.7 151 Mn kDa 41983 37426 54776 85947 Mw kDa 259895 160229 137423179524 Mz kDa 1173716 460875 242959 321119 Mp kDa 107648 50516 118926150440 D 6.1 4.3 2.5 2.1

TABLE 2 Max Thermal Force Bonding Mach. Temper- Dir Elong @ break MaxForce Elong @ break ature (N/5 Mach. dir Trans dir Trans dir Blend (°C.) cm) (%) (N/5 cm) (%) Poly 142 27 85 12 95 1 Poly 148 35 60 14 65 1Pure 142 13 25 6 20 miPP Pure 148 12 20 6 20 miPP

TABLE 3 Take-up: 1600 m/min followed by drawing (SR = 1.3) Tenacity @ wt% wt % Titre 10% Elong @ max Sigma @ max znPP miPP (dtex) (cN/tex) (%)(cN/tex) 100 0 2.6 9.6 407 20.0 80 20 2.6 9.2 379 19.8 60 40 2.6 9.2 39721.5 40 60 2.6 8.9 339 20.7 20 80 2.6 8.8 281 22.3 15 85 2.5 7.8 35223.9 10 90 2.5 8.2 322 26.7 5 95 2.5 8.6 312 29.3 2 98 2.5 9.2 256 31.40 100 2.6 11.5 164 32.3

TABLE 4 Direct Take-up: 1600 m/min Tenacity @ wt % wt % Titre 10% Elong@ max Sigma @ max znPP miPP (dtex) (cN/tex) (%) (cN/tex) 100 0 2.6 6.8435 14.8 80 20 2.6 6.5 513 15.9 60 40 2.5 6.6 456 16.4 40 60 2.6 6.3 46117.1 20 80 2.6 6.1 443 20.3 15 85 2.2 5.8 485 18.9 10 90 2.4 5.8 42420.4 5 95 2.6 5.4 496 20.5 2 98 2.6 5.5 363 24.0 0 100 2.6 6.2 285 27.9

What is claimed is:
 1. A polypropylene fibre including greater than 50%by weight of a first isotactic polypropylene produced by a Ziegler-Nattacatalyst, from 5 to less than 50% by weight of a second isotacticpolypropylene produced by a metallocene catalyst and up to 15% by weightof a syndiotactic polypropylene (sPP).
 2. A polypropylene fibreaccording to claim 1 including from 10 to less than 50% by weight of thesecond isotactic polypropylene.
 3. A polypropylene fibre according toclaim 2 including from 60 to 80% by weight of the first isotacticpolypropylene and from 20 to 40% by weight of the second isotacticpolypropylene.
 4. A polypropylene fibre according to claim 1 wherein thesecond polypropylene is a homopolymer, copolymer or terpolymer ofisotactic polypropylene or a blend of such polymers.
 5. A polypropylenefibre according to claim 4 wherein the second polypropylene has adispersion index (D) of from 1.8 to
 8. 6. A polypropylene fibreaccording to claim 4 wherein the second polypropylene has a meltingtemperature in the range of from 80 to 161° C.
 7. A polypropylene fibreaccording to claim 1 wherein the second polypropylene has a melt flowindex (MFI) of from 1 to 2500 g/10 mins.
 8. A polypropylene fibreaccording to claim 7 wherein the first polypropylene has a dispersionindex of from 3 to
 12. 9. A polypropylene fibre according to claim 1wherein the first polypropylene homopolymer has a melting temperature inthe range of from 159 to 169° C.
 10. A polypropylene fibre according toclaim 1 wherein the amount of syndiotactic polypropylene (sPP) is up to10% by weight.
 11. A polypropylene fibre according to claim 1 whereinthe sPP is a homopolymer, a random copolymer, a block copolymer or aterpolymer or a blend of such polymers.
 12. A polypropylene fibreaccording to claim 1 wherein the sPP has a melting temperature of up toabout 130° C.
 13. A fabric produced from the polypropylene fibreaccording to claim
 1. 14. A product including a fabric according toclaim 1, the product being selected from a filter, personal wipe,diaper, feminine hygiene product, incontinence product, wound dressing,bandage, surgical gown, surgical drape, protective cover, geotextilesand outdoor fabrics.